CN115800608A - Drive device and vehicle - Google Patents

Abstract

The motor shaft of the drive extends along a first axis of rotation extending in an axial direction. The gear portion is connected to one axial side of the motor shaft. The housing tube portion extends in the axial direction and holds the stator on the radially inner side surface. The first cover is attached to the other end portion in the axial direction of the housing tube. The first bearing of the motor bearing for rotatably supporting the motor shaft is a rolling bearing disposed in the first lid portion, and rotatably supports the motor shaft on the other side in the axial direction than the rotor. The motor shaft is electrically insulated from the first cover portion by the first bearing.

Description

Drive device and vehicle

Technical Field

The present invention relates to a drive device.

Background

Currently, a technique for performing static elimination on a motor shaft of an electric motor is known. For example, a charge dissipation assembly as a static eliminator is in contact with the radially outer side surface of the motor shaft. Thereby, the shaft voltage of the motor shaft is grounded (see, for example, japanese patent laid-open No. 2005-124391).

Documents of the prior art

Patent literature

Patent document 1: japanese patent laid-open No. 2005-124391.

Disclosure of Invention

Technical problem to be solved by the invention

However, if the conductive path is formed only in the motor shaft, the electric charge of the motor shaft may not be sufficiently discharged. In particular, in a drive device mounted on an electric vehicle, a rotor, a stator, and a gear portion are housed in a case, and it is important to control potential variation occurring in the case. For example, since the control of the driving current of the stator by the inverter causes potential variation in the motor shaft, galvanic corrosion is likely to occur. The electro-corrosion is a phenomenon that the inner circumferential surfaces of the outer ring and the inner ring of the rolling bearing are damaged in a wavy manner. The electric corrosion occurs due to electric discharge in the rolling bearing by the electric current flowing from the shaft to the rolling bearing. Therefore, inhibition and prevention of galvanic corrosion are important technical issues.

The object of the present invention is to more effectively suppress or prevent galvanic corrosion.

Technical scheme for solving technical problem

An exemplary driving apparatus of the present invention includes a motor shaft, a rotor, a stator, a gear portion, and a housing. The motor shaft extends along a first rotation axis extending in an axial direction and is rotatable centering on the first rotation axis. The rotor is rotatable with the motor shaft. The stator is disposed radially outward of the rotor. The gear portion is connected to one axial side of the motor shaft. The housing houses the rotor, the stator, and the gear portion. The housing has a housing barrel, a first cover, a second cover, and a motor bearing. The housing tube portion extends in the axial direction and holds the stator on a radially inner side surface. The first cover is attached to the other end portion in the axial direction of the housing tube. The second cover portion is disposed on one axial side of the outer shell tube portion, and extends in a direction intersecting the first rotation axis. The motor bearing rotatably supports the motor shaft. The motor bearing has a first bearing and a second bearing. The first bearing is a rolling bearing disposed in the first cover portion, and rotatably supports the motor shaft on the other side in the axial direction than the rotor. The second bearing is disposed on the second cover, and rotatably supports the motor shaft on one side in the axial direction of the rotor. The motor shaft is electrically insulated from the first cover portion by a first bearing.

An exemplary vehicle of the invention includes the drive device.

Effects of the invention

According to the exemplary driving apparatus and vehicle of the present invention, the electric corrosion can be more effectively suppressed or prevented.

Drawings

Fig. 1 is a conceptual diagram illustrating a configuration example of a driving device.

Fig. 2 is a conceptual diagram illustrating a static electricity eliminating path of the driving device in the embodiment.

Fig. 3 is a schematic diagram showing an example of a vehicle equipped with a driving device.

Fig. 4A is a sectional view showing a structural example of the motor bearing.

Fig. 4B is a cross-sectional view showing a first modification of the structure of the motor bearing.

Fig. 4C is a cross-sectional view showing a second modification of the structure of the motor bearing.

Fig. 5 is a sectional view showing a configuration example of the first drive bearing and the second drive bearing.

Fig. 6 is a sectional view showing a configuration example of the first intermediate bearing and the second intermediate bearing.

Fig. 7 is a schematic configuration diagram of a driving device according to a modification.

Fig. 8 is a conceptual diagram illustrating a static electricity eliminating path of the driving device in the modification.

Description of the symbols

100. Drive device

200. Battery with a battery cell

300. Vehicle with a steering wheel

301. Vehicle body

1. Motor shaft

11. Rotor shaft

111. Shaft through hole

112. Inlet port

12. Gear shaft

121. Inlet port

13. Shaft wall part

2. Motor with a stator and a rotor

21. Rotor

211. Rotor core

2111. Rotor through hole

212. Magnet body

22. Stator with a stator core

221. Stator core

222. Coil part

2221. Coil edge terminal

3. Gear part

31. Reduction gear

311. First gear

312. Second gear

313. Third gear

314. Intermediate shaft

32. Differential gear

321. Fourth gear

4. Outer casing

401. Motor casing

402. Gear casing

403. Inverter casing

4031. Inverter with a voltage regulator

41. A first outer shell cylinder part

42. Side plate part

4201. Side plate through hole

4202. First drive shaft through hole

421. Second rotor bearing retainer

4211. Second rotor bearing

422. First gear bearing retainer

4221. First gear bearing

423. First intermediate bearing holder

4231. First intermediate bearing

424. First drive bearing retainer

4241. First drive bearing

43. Shell cover part

431. First rotor bearing retainer

4311. First rotor bearing

4312. Opening part

432. First drive shaft through hole

433. First drive bearing retainer

4331. First drive bearing

44. Cover member

45. Second housing barrel

46. Gear cover part

460. Second driving shaft through hole

461. Second gear bearing retainer

4611. Second gear bearing

462. Second intermediate bearing retainer

4621. Second intermediate bearing

463. Second drive bearing retainer

4631. Second drive bearing

464. Flow path

465. Receiving disc part

47. Second gear bearing retainer

471. Second gear bearing

5. Fluid circulation unit

51. Piping section

52. Pump and method of operating the same

53. Cooling unit

54. Fluid reservoir

6. Ground connection

71. Track ring

711. Inner side track ring

712. Outer side track ring

72. Rolling body

73. First insulating member

74. Second insulating member

81. Track ring

811. Inner side track ring

812. Outer side track ring

82. Rolling body

83. Lubricating material

91. Track ring

911. Inner side track ring

912. Outer side track ring

92. Rolling element

93. Lubricating material

F fluid

P fluid reservoir

Ds drive shaft

Ds1 first drive shaft

Ds2 second drive shaft

J1 First axis of rotation

J2 Second axis of rotation

J3 A third axis of rotation.

Detailed Description

Hereinafter, exemplary embodiments will be described with reference to the drawings.

In the present specification, a direction parallel to the first rotation axis J1 of the motor 2 is referred to as an "axial direction" of the drive device 100. As shown in fig. 1, the gear portion 3 side is set as one axial side D1, and the motor 2 side is set as the other axial side D2. A radial direction perpendicular to a predetermined axis such as the first rotation axis J1 is simply referred to as a "radial direction", and a circumferential direction around the predetermined axis such as the first rotation axis J1 is simply referred to as a "circumferential direction".

In this specification, the term "parallel" in a positional relationship between any one of an orientation, a line, and a plane and any other one includes not only a state where both extend to any point without crossing each other at all, but also a state where both extend substantially parallel to each other. Further, "perpendicular" includes not only a state where both intersect each other at 90 degrees but also a substantially perpendicular state. That is, "parallel" and "perpendicular" include a state in which there is an angular deviation in the positional relationship of the two to the extent that does not depart from the gist of the present invention.

In addition, in the present specification, the term "annular" includes not only a shape in which the entire circumferential region centered on a predetermined axis such as the first rotation axis J1 is continuously connected but also a shape in which one or more slits are provided in a part of the entire region centered on the predetermined axis. The present invention also includes a shape in which a closed curve is drawn on a curved surface intersecting with a predetermined axis line with the predetermined axis line as a center.

In the present specification, "extend" in a predetermined direction includes not only a structure in which the extending direction extends strictly in the predetermined direction but also a structure in which the extending direction extends substantially in the predetermined direction. That is, "extending" in a predetermined direction includes a structure in which there is a directional deviation from the predetermined direction to such an extent that does not depart from the gist of the present invention. The same is true for "expansion" in a given direction.

< 1. Embodiment >

Fig. 1 is a conceptual diagram illustrating a configuration example of a drive device 100. Fig. 2 is a conceptual diagram illustrating a static electricity elimination path of the driving device 100 in the embodiment. Fig. 3 is a schematic diagram showing an example of a vehicle 300 on which the driving device 100 is mounted. Fig. 1 and 2 are conceptual views, and the arrangement and dimensions of the respective portions are not necessarily exactly the same as those of the actual drive device 100. In fig. 2, a thick solid line with an arrow indicates the static electricity elimination path. Figure 3 conceptually illustrates a vehicle 300.

In the present embodiment, as shown in fig. 3, the drive device 100 is mounted on a vehicle 300 that uses at least a motor as a power source. The vehicle 300 is, for example, a Hybrid Vehicle (HV), a plug-in hybrid vehicle (PHV), or an Electric Vehicle (EV). The vehicle 300 includes the driving apparatus 100. In the vehicle 300, the occurrence of galvanic corrosion at the motor bearings 4311, 4211, 4221, 4611 (particularly, the first rotor bearing 4311) described later, which support the motor shaft 1 (particularly, the rotor shaft 11) of the drive device 100, can be more effectively suppressed or prevented. In fig. 3, the driving device 100 drives the front wheels of a vehicle 300. But not limited to the example of fig. 3, the driving device 100 may be any device as long as it drives at least any one wheel. Further, the vehicle 300 has a battery 200. The battery 200 stores electric power for supply to the driving device 100.

As shown in fig. 1 to 3, the drive device 100 includes a motor shaft 1, a motor 2, a gear portion 3, a housing 4, a fluid circulation portion 5, and a ground connection portion 6.

< 1-1. Motor shaft 1 >

The motor shaft 1 extends in the axial direction along the first rotation axis J1. The first rotation axis J1 extends in the axial direction. As described above, the driving device 100 includes the motor shaft 1. The motor shaft 1 is rotatable about the first rotation axis J1. As shown in fig. 1, the motor shaft 1 is rotatably supported by the housing 4 via a first rotor bearing 4311, a second rotor bearing 4211, a first gear bearing 4221, and a second gear bearing 4611.

In addition, hereinafter, the first rotor bearing 4311 and the second rotor bearing 4211 are sometimes collectively referred to as " rotor bearings 4211, 4311". The rotor bearings 4211 and 4311 rotatably support the rotor shaft 11. The housing 4 has rotor bearings 4211, 4311.

The first gear bearing 4221 and the second gear bearing 4611 may be collectively referred to as " gear bearings 4221 and 4611". The gear bearings 4221 and 4611 support the motor shaft 1 to be rotatable together with the rotor bearings 4211 and 4311. The housing 4 has gear bearings 4221, 4611.

The first rotor bearing 4311, the second rotor bearing 4211, the first gear bearing 4221, and the second gear bearing 4611 may be collectively referred to as " motor bearings 4311, 4211, 4221, and 4611". The motor bearings 4311, 4211, 4221, and 4611 rotatably support the motor shaft 1. The housing 4 has motor bearings 4311, 4211, 4221, 4611.

The motor shaft 1 has a cylindrical shape extending in the axial direction. The motor shaft 1 has conductivity, and is made of metal in the present embodiment. The fluid F flows inside the motor shaft 1. The flow path of the fluid F including the inside of the motor shaft 1 is an example of the "fluid flow path" in the present invention. The drive device 100 further comprises the above-mentioned fluid F. In the present embodiment, the Fluid F is a lubricating Fluid for lubricating the gear portion 3, the bearings of the drive device 100, and the like, and is, for example, ATF (Automatic Transmission Fluid). The fluid F also serves as a refrigerant for cooling the motor 2 and the like. The fluid F flowing inside the motor shaft 1 can be supplied to the motor 2, the first rotor bearing 4311, the second rotor bearing 4211, and the like through the shaft insertion hole 111 in accordance with the rotation of the motor shaft 1. Therefore, the stator 22 (particularly, the coil edge 2221 described later) and the rotor bearings 4211, 4311 and the like can be cooled by the fluid F.

The motor shaft 1 includes a rotor shaft 11 and a gear shaft 12. The rotor shaft 11 is an example of the "first shaft" of the present invention, and holds the rotor 21. The gear shaft 12 is an example of a "second shaft" of the present invention, and is connected to an end portion of the rotor 11 on the one axial side D1. The gear portion 3 is connected to a gear shaft 12. The rotor shaft 11 and the gear shaft 12 are cylindrical and extend in the axial direction, and extend along the first rotation axis J1.

In the present embodiment, both are spline-fitted. When the rotor shaft 11 and the gear shaft 12 are spline-fitted, the external teeth formed on the gear shaft 12 side come into contact with the internal teeth formed on the rotor shaft 11 side when the drive device 100 is in the power running state and the regenerative state.

Further, the rotor shaft 11 and the gear shaft 12 may be coupled to each other by a screw coupling using a male screw and a female screw, or may be joined to each other by a fixing method such as press fitting or welding, without being limited to the above examples. When a fixing method such as press-fitting or welding is employed, a serration structure (serration) in which a recess and a projection extending in the axial direction are combined may be employed. With the above configuration, rotation can be reliably transmitted. The present embodiment is not limited to the example, and the motor shaft 1 may be a single member.

Rotor bearings 4211, 4311 are disposed at both axial end portions of the rotor shaft 11. The rotor bearings 4211 and 4311 rotatably support both axial end portions of the rotor shaft 11.

The motor bearings 4311, 4211, 4221, 4611 have a first rotor bearing 4311. The first rotor bearing 4311 is an example of the "first bearing" of the present invention. The first rotor bearing 4311 is a rolling bearing disposed in a housing lid portion 43 described later, and rotatably supports the motor shaft 1 on the other axial side D2 of the rotor 21. As described later, the first rotor bearing 4311 has an insulating portion (refer to fig. 4A to 4C described later). Thereby, the motor shaft 1 (that is, the rotor shaft 11) is electrically insulated from the housing lid portion 43 by the first rotor bearing 4311.

As shown in fig. 1 and the like, the first housing tube portion 41 and the housing cover portion 43 are different members. Therefore, the end portion of the motor shaft 1 on the other axial side D2 may swing about the first rotation axis J1 due to the tolerance stack-up when the housing 4 including the first housing tube 41 and the housing cover 43 is assembled with the motor shaft 1. Accordingly, in the rolling bearing on the other axial side D2 side of the motor shaft 1 (that is, the first rotor bearing 4311), the fluid F such as the lubricating oil is likely to be biased, and an increase or decrease in the fluid F in the direction around the first rotation axis J1 due to the local bias may be generated.

Further, the fluid F cooled in the cooling unit 53 is supplied to the motor bearings 4311, 4211, 4221, 4611. Here, the first rotor bearing 4311 is disposed in the housing lid portion 43, and is thus close to the outside of the drive device 100. Further, the fluid F whose temperature has risen by the heat source such as the stator 22 and the gear portion 3 is less likely to be supplied to the first rotor bearing 4311 than the fluid F supplied to the other motor bearings 4211, 4221, 4611. Therefore, the fluid F in the first rotor bearing 4311 is likely to be thickened in accordance with the decrease in temperature. Therefore, at the first rotor bearing 4311, local increase and decrease of the fluid F in the direction around the first rotation axis J1 more easily occurs.

Generally, in a rolling bearing, the more the fluid F such as lubricating oil between a pair of raceway rings (see fig. 4A to 6, for example), the higher the potential difference between the pair of raceway rings. Therefore, at a portion where the fluid F is large, the potential difference tends to exceed the dielectric breakdown voltage.

Therefore, at the first rotor bearing 4311, galvanic corrosion is more likely to occur than the other motor bearings 4211, 4221, 4611.

Therefore, the end portion on the other axial side D2 side of the motor shaft 1 (particularly, the rotor shaft 11) can be electrically insulated from the housing lid portion 43 by the electrical insulation at the first rotor bearing 4311. Therefore, the galvanic corrosion of the first rotor bearing 4311, which is most likely to occur, can be suppressed or prevented. That is, the galvanic corrosion can be more effectively suppressed or prevented.

Further, since the gear shaft 12 is connected to the end portion on the one axial side D1 side of the rotor shaft 11, the above-described cumulative tolerance is liable to become further large. Therefore, the wobbling of the end portion of the rotor shaft 11 on the other axial side D2 is likely to increase, and the local increase and decrease of the fluid F in the first rotor bearing 4311 are also likely to occur. Even in the above-described structure, since the rotor shaft 11 and the housing lid portion 43 are electrically insulated by the first rotor bearing 4311, electrical corrosion of the first rotor bearing 4311 can be suppressed or prevented.

In addition, as described later, the drive device 100 further includes a fluid flow path. The fluid flow path supplies the fluid F for lubricating the rotor bearings 4211 and 4311 to the rotor bearings 4211 and 4311. For example, in the present embodiment, the fluid flow path includes a flow path constituted by the receiving disc part 465, the flow path 464, the inside of the motor shaft 1, the shaft through-hole 111, and the rotor through-hole 2111, which will be described later. Further, the fluid flow path includes a fluid circulation portion 5. In this way, since reduction or shortage of the lubricating fluid F in the rotor bearings 4211, 4311 can be suppressed or prevented, seizure of the rotor bearings 4211, 4311 (the japanese sintering: the manufacture of the brick 1236565.

Furthermore, the motor bearings 4311, 4211, 4221, 4611 have a second rotor bearing 4211. The second rotor bearing 4211 is an example of the "second bearing" of the present invention. The second rotor bearing 4211 is a rolling bearing disposed in a side plate portion 42 described later of the housing 4, and rotatably supports the motor shaft 1 on the axial direction side D1 of the rotor 21. Specifically, the second rotor bearing 4211 rotatably supports an end portion of the rotor shaft 11 on the one axial direction D1 side. As described later, the second rotor bearing 4211 has an insulating portion. The motor shaft 1 is electrically insulated from the side plate portion 42 by a second rotor bearing 4211. In this way, since the motor shaft 1 (particularly, the end portion on the one axial side D1 side of the rotor shaft 11) can be electrically insulated from the side plate portion 42 by the second rotor bearing 4211, galvanic corrosion of the second rotor bearing 4211 can be suppressed or prevented.

Further, at the one axial direction side D1 of the motor shaft 1, electric charges generated due to potential variation flow to the gear portion 3 and the like and are dispersed. Therefore, the degree of occurrence of galvanic corrosion at the second rotor bearing 4211 and the degree thereof are lower than those at the first rotor bearing 4311. Therefore, the electrical resistance at the first rotor bearing 4311 is greater than the electrical resistance at the second rotor bearing 4211. With the above configuration, the electric corrosion of the first rotor bearing 4311, which is likely to cause electric corrosion, can be more effectively suppressed or prevented. However, the above example does not exclude the structure in which the electric resistance at the first rotor bearing 4311 is equal to or lower than the electric resistance at the second rotor bearing 4211.

Further, gear bearings 4221, 4611 are disposed at both axial end portions of the gear shaft 12. The gear bearings 4221 and 4611 rotatably support both axial end portions of the gear shaft 12.

Next, the motor shaft 1 has a shaft insertion hole 111. The shaft insertion hole 111 is disposed in the rotor shaft 11 and radially penetrates the cylindrical rotor shaft 11. The number of the shaft penetrating holes 111 may be single or plural. When the motor shaft 1 rotates, the fluid F inside it flows out to the outside of the rotor shaft 11 through the shaft through hole 111 by the centrifugal force. In the present embodiment, as shown in fig. 1, the shaft insertion hole 111 is disposed on the other axial side D2 from the end portion on the one axial side D1 of the rotor 21 and on the one axial side D1 from the end portion on the other axial side D2 of the rotor 21. The shaft through hole 111 is connected to a rotor through hole 2111 described later. However, the shaft insertion hole 111 is not limited to the example of fig. 1, and may be disposed on one axial side D1 of the end portion on the one axial side D1 of the rotor 21 and on the other axial side D2 of the second rotor bearing 4211, or may be disposed on the other axial side D2 of the end portion on the other axial side D2 of the rotor 21 and on the one axial side D1 of the first rotor bearing 4311. The above illustration does not exclude a configuration in which the shaft through hole 111 and the rotor through hole 2111 are omitted.

The motor shaft 1 further has an inflow port 121. The inlet 121 is an opening at an end portion on the axial direction side D1 of the motor shaft 1, and in the present embodiment, an opening at an end portion on the axial direction side D1 of the gear shaft 12 described later. The inlet 121 is connected to a flow passage 464 of the gear cover 46 described later. The fluid F flows from the flow path 464 into the motor shaft 1 through the inflow port 121.

The motor shaft 1 also has a shaft wall 13. The shaft wall portion 13 is disposed inside the rotor shaft 11 at the other axial side D2 side thereof, and expands in the radial direction. The shaft wall portion 13 is disposed on the other axial side D2 of the shaft through hole 111. That is, the shaft wall portion 13 closes the opening at the end portion on the other axial side D2 side of the rotor shaft 11. The radially outer end of the shaft wall portion 13 is connected to the inner surface of the rotor shaft 11. The shaft wall portion 13 may be integral with the rotor shaft 11 or may be separate from the rotor shaft 11.

< 1-2. Motor 2 >

The motor 2 is, for example, a dc brushless motor. The motor 2 is a drive source of the drive apparatus 100 and is driven by electric power supplied from the inverter 4031 (see fig. 3). The motor 2 is an inner rotor type in which a rotor 21 is rotatably disposed radially inside a stator 22. As shown in fig. 1, the motor 2 has a rotor 21 and a stator 22.

< 1-2-1. Rotor 21 >

The rotor 21 is rotatable together with the motor shaft 1. The drive device 100 includes a rotor 21. The rotor 21 is fixed to the motor shaft 1 and is rotatable about the first rotation axis J1. The rotor 21 is rotated by supplying electric power from the inverter 4031 of the drive device 100 to the stator 22. The rotor 21 has a rotor core 211 and a magnet 212. The rotor core 211 is a magnetic body, and is formed by laminating thin electromagnetic steel plates in the axial direction, for example. The rotor core 211 is fixed to a radially outer side surface of the rotor shaft 11. A plurality of magnets 212 are fixed at the rotor core 211. The plurality of magnets 212 have magnetic poles alternately arranged in the circumferential direction.

Further, the rotor core 211 has a rotor through-hole 2111. The rotor through-hole 2111 axially penetrates the rotor core 211 and is connected to the shaft through-hole 111. The rotor through-hole 2111 serves as a flow path for the fluid F that also functions as a refrigerant. When the rotor 21 rotates, the fluid F flowing through the motor shaft 1 can flow into the rotor through-hole 2111 through the shaft through-hole 111. The fluid F flowing into the rotor through-hole 2111 can flow out from both axial end portions of the rotor through-hole 2111. The fluid F thus discharged flies toward the stator 22 and cools, for example, a coil portion 222 (particularly, a coil edge 2221) described later. The fluid F flowing out flies toward the rotor bearings 4211, 4311 and the like rotatably supporting the motor shaft 1, lubricates them, and cools them.

< 1-2-2. Stator 22 >

The stator 22 is disposed radially outward of the rotor 21. The driving device 100 includes a stator 22. The stator 22 is radially opposed to the rotor 21 with a gap therebetween. The stator 22 has a stator core 221 and a coil portion 222. The stator 22 is held by a first housing tube 41 described later and fixed to the inner surface thereof. The stator core 221 includes a plurality of magnetic pole teeth (not shown) extending from an inner surface of an annular yoke (not shown) to a radially inner side. The coil portion 222 is formed by winding a wire around the magnetic pole teeth via an insulator (not shown). The coil portion 222 has a coil side end 2221 protruding from an axial end face of the stator core 221.

< 1-3. Gear part 3 >

Next, the gear portion 3 is connected to the axial direction one side D1 of the motor shaft 1. As described previously, the drive device 100 includes the gear portion 3. The gear portion 3 is a power transmission device that transmits the power of the motor 2 to a drive shaft Ds described later. The gear portion 3 has a speed reduction device 31 and a differential device 32.

< 1-3-1. Reduction gear 31 >

The reduction gear 31 is connected to the gear shaft 12. The reduction device 31 reduces the rotation speed of the motor 2, and increases the torque output from the motor 2 according to its reduction ratio. The reduction gear 31 transmits the torque output from the motor 2 to the differential device 32. The reduction gear 31 has a first gear 311, a second gear 312, a third gear 313, and an intermediate shaft 314.

The first gear 311 is fixed to a radially outer side surface of the motor shaft 1 at one axial side D1 side of the motor shaft 1. The gear portion 3 has a first gear 311. For example, the first gear 311 is disposed on the radially outer side surface of the gear shaft 12. The first gear 311 may be integrated with the gear shaft 12, or may be separate from the gear shaft 12 and firmly fixed to the radially outer side surface of the gear shaft 12. The first gear 311 is rotatable together with the motor shaft 1 about the first rotation axis J1.

The intermediate shaft 314 extends along the second rotation axis J2 and is rotatable about the second rotation axis J2. In addition, the second rotation axis J2 extends in the axial direction. The gear portion 3 has an intermediate shaft 314. Both ends of the intermediate shaft 314 are supported to be rotatable about the second rotation axis J2 by a first intermediate bearing 4231 and a second intermediate bearing 4621. In addition, hereinafter, the first intermediate bearing 4231 and the second intermediate bearing 4621 are sometimes collectively referred to as " intermediate bearings 4231, 4621".

The second gear 312 is fixed to a radially outer side surface of the intermediate shaft 314 and meshes with the first gear 311. The third gear 313 is fixed to a radially outer side surface of the intermediate shaft 314. The gear portion 3 includes a second gear 312 and a third gear 313. The third gear 313 is disposed on the other axial side D2 from the second gear, and meshes with the fourth gear 321 of the differential device 32. The second gear 312 and the third gear 313 may be integrated with the intermediate shaft 314, respectively, or may be separate from the intermediate shaft 314 and firmly fixed to the radially outer surface of the intermediate shaft 314. The second gear 312 and the third gear 313 are rotatable together with the intermediate shaft 314 about the second rotation axis J2.

The torque of the motor shaft 1 is transmitted from the first gear 311 to the second gear 312. Then, the torque transmitted to the second gear 312 is transmitted to the third gear 313 via the intermediate shaft 314. Further, the torque is transmitted from the third gear 313 to the fourth gear 321.

< 1-3-2. Differential device 32 >

The differential device 32 is attached to the drive shaft Ds, and transmits the torque transmitted from the reduction gear 31 to the drive shaft Ds. As described above, the gear portion 3 has the differential gear 32. The differential device 32 has a fourth gear 321 that meshes with the third gear 313, and outputs torque of the fourth gear 321 to the drive shaft Ds. The fourth gear 321 is a so-called ring gear. The drive shaft Ds has a first drive shaft Ds1 and a second drive shaft Ds2. The first drive shaft Ds1 is mounted on the other axial side D2 of the differential device 32. The second drive shaft Ds2 is attached to one axial side D1 of the differential device 32. The differential device 32 transmits torque to the drive shafts Ds1, ds2 on both sides in the axial direction while absorbing a difference in rotational speed between the drive shafts Ds1, ds2 on both sides in the axial direction when the vehicle 300 turns, for example.

< 1-4. Shell 4 >

The housing 4 houses the motor shaft 1, the motor 2 (particularly, the rotor 21 and the stator 22), and the gear portion 3. As previously mentioned, the drive device 100 comprises a housing 4. The housing 4 has a first housing tube section 41, a side plate section 42, a housing lid section 43, a cover member 44, a second housing tube section 45, and a gear lid section 46. The first housing tube 41, the side plate 42, the housing cover 43, the cover member 44, the second housing tube 45, and the gear cover 46 are formed using, for example, a conductive material, and in the present embodiment, a metal material such as iron, aluminum, or an alloy thereof is used. Further, in order to suppress dissimilar metal contact corrosion at the contact portion, it is preferable that the above members are formed using the same material. However, the present invention is not limited to the above examples, and the above members may be formed using a material other than a metal material, or at least a part of the above members may be formed using a different material.

The housing 4 further includes a motor housing 401 and a gear housing 402. The motor housing 401 and the gear housing 402 will be described later. The housing 4 also has an inverter housing 403. The inverter case 403 houses an inverter 4031 that supplies drive current to the stator 22.

< 1-4-1. First housing cylindrical portion 41 >

The first housing tube portion 41 is a tube shape extending in the axial direction, and is an example of the "housing tube portion" of the present invention. As described above, the housing 4 has the first housing tube portion 41. The stator 22 is fixed to the inner surface of the first housing tube 41. The motor 2 including the rotor 21 and the stator 22, and the fluid reservoir 54 described later are disposed inside the first housing tube 41.

< 1-4-2 > side plate part 42 >

The side plate portion 42 is disposed on the one axial side D1 of the first housing tube portion 41 and extends in a direction intersecting the first rotation axis J1. As described above, the housing 4 has the side plate portion 42. The side plate 42 is an example of the "second cover" of the present invention. The side plate portion 42 is disposed at an end portion on the one axial side D1 of the first housing tube portion 41, and covers the end portion on the one axial side D1 of the first housing tube portion 41. The side plate 42 covers the end of the second housing tube 45 on the other axial side D2. The side plate portion 42 extends in a direction intersecting the first rotation axis J1, and divides the first housing tube portion 41 and the second housing tube portion 45. In the present embodiment, the first housing tube portion 41 and the side plate portion 42 are integrated. Thereby, their rigidity can be improved. The present invention is not limited to the above examples, and both may be separate.

The side plate portion 42 has a side plate through hole 4201 and a first drive shaft through hole 4202. The side plate through hole 4201 and the first drive shaft through hole 4202 axially penetrate the side plate portion 42. The center of the side plate penetration hole 4201 coincides with the first rotation axis J1. A motor shaft 1 is inserted into the side plate through hole 4201. The center of the first drive shaft through hole 4202 coincides with the third rotation axis J3. The first drive shaft Ds1 is inserted into the first drive shaft through hole 4202. An oil seal (not shown) for sealing between the first drive shaft Ds1 and the first drive shaft through hole 4202 is disposed in a gap therebetween.

The side plate portion 42 further includes a second rotor bearing holder 421, a first gear bearing holder 422, a first intermediate bearing holder 423, and a first drive bearing holder 424. The second rotor bearing holder 421 is disposed on the other axial side D2 of the inner surface of the side plate through hole 4201, and holds the second rotor bearing 4211. The second rotor bearing 4211 rotatably supports an end portion of the rotor shaft 11 on the one axial side D1 side. The first gear bearing holder 422 is disposed on the axial direction side D1 of the inner surface of the side plate through hole 4201, and holds the first gear bearing 4221. The first gear bearing 4221 is another example of the "second bearing" of the present invention, and rotatably supports the end portion of the gear shaft 12 on the other axial side D2 side. The first intermediate bearing holder 423 is disposed on an end surface of the side plate portion 42 on the one axial side D1, and holds the first intermediate bearing 4231. The first intermediate bearing 4231 rotatably supports the end portion of the intermediate shaft 314 on the other axial side D2 side. The first drive bearing holder 424 is disposed on the inner surface of the first drive shaft through hole 4202, and holds the first drive bearing 4241. The first drive bearing 4241 rotatably supports the first drive shaft Ds1.

< 1-4-3. Housing cover part 43 >

The housing cover portion 43 is expanded in a direction intersecting the first rotation axis J1, and covers an end portion on the other axial side D2 side of the first housing tube portion 41. As previously described, the housing 4 includes a housing cover portion 43. The housing cover 43 is an example of the "first cover" of the present invention, and is attached to the end of the first housing tube 41 on the other axial side D2. The fixing of the housing cover 43 to the first housing tube 41 is performed by, for example, screws, but is not limited thereto, and a method of firmly fixing the housing cover 43 to the first housing tube 41 by screwing, press-fitting, or the like can be widely used. Thereby, the housing lid portion 43 can be brought into close contact with the end portion on the other axial side D2 of the first housing tube portion 41. The term "close contact" means that the following sealing properties are provided: the fluid F inside the member does not leak to the outside, and foreign substances such as water, dust, and dirt on the outside do not enter. The same applies hereinafter with respect to the abutment.

Further, the housing cover portion 43 has a first rotor bearing holder 431. The first rotor bearing holder 431 holds the first rotor bearing 4311. The first rotor bearing 4311 rotatably supports an end portion of the rotor shaft 11 on the other axial side D2 side. The first rotor bearing holder 431 has an opening 4312 through which the rotor shaft 11 is inserted. The opening 4312 axially penetrates the housing lid 43 and surrounds the first rotation axis J1 when viewed in the axial direction.

< 1-4-4. Cover Member 44 >

The cover member 44 is disposed on the end surface of the housing lid portion 43 on the other axial side D2, and covers the opening portion 4312 and the end portion of the motor shaft 1 on the other axial side D2. Examples of the attachment of the cover member 44 to the housing cover portion 43 include, but are not limited to, screw fastening, and a method of firmly fixing the cover member 44 to the housing cover portion 43 by screwing, press fitting, or the like is widely used. A rotation detector (e.g., resolver) or the like for detecting the rotation angle of the rotor can be housed in the space surrounded by the cover member 44 and the housing lid portion 43. In addition, a static eliminator for electrically connecting the motor shaft 1 and the housing 4 may be disposed in the space.

< 1-4-5. Second housing cylindrical part 45 >

The second casing tubular portion 45 is tubular surrounding the first rotation axis J1, and extends in the axial direction. The end portion of the second casing tube 45 on the other axial side D2 is connected to the side plate 42 and covered by the side plate 42. In the present embodiment, the second casing tube 45 is detachably attached to the end portion of the side plate 42 on the one axial side D1. The second housing tube 45 is fixed to the side plate 42 by screws, but the present invention is not limited thereto, and a method of firmly fixing the second housing tube 45 to the side plate 42 by screwing, pressing, or the like can be widely used. Thereby, the second casing tube 45 is in close contact with the end of the side plate 42 on the one axial side D1.

< 1-4-6. Gear cover part 46 >

The gear cover 46 is disposed at the end portion on the one axial side D1 of the second casing tube 45, and covers the end portion on the one axial side D1 of the second casing tube 45. The gear cover portion 46 is disposed on the axial direction side D1 of the first housing tube portion 41 and extends in a direction intersecting the first rotation axis J1. The gear cover portion 46 is another example of the "second cover portion" of the present invention. As previously described, the housing 4 includes the gear cover portion 46. In the present embodiment, the second housing cylindrical portion 45 and the gear cover portion 46 are integrated. The present invention is not limited to the above examples, and both may be separate.

The gear cover portion 46 has a second drive shaft through hole 460. The second drive shaft penetrating hole 460 penetrates the gear cover portion 46 in the axial direction. The center of the second drive shaft through hole 460 coincides with the third rotation axis J3. The second drive shaft Ds2 is inserted into the second drive shaft through hole 460. An oil seal (not shown) is disposed in a gap between the second drive shaft Ds2 and the second drive shaft through hole 460.

The gear cover portion 46 further includes a second gear bearing holder 461, a second intermediate bearing holder 462, and a second drive bearing holder 463. The second gear bearing holder 461 and the second intermediate bearing holder 462 are disposed on the end surface of the gear cover portion 46 on the other axial side D2 side. The second gear bearing holder 461 holds a second gear bearing 4611. In addition, hereinafter, the first gear bearing holder 422 and the second gear bearing holder 461 are sometimes collectively referred to as " gear bearing holders 422, 461". The housing 4 has gear bearing retainers 422, 461. The gear bearing holders 422 and 461 hold gear bearings 4221 and 4611.

The second gear bearing 4611 is another example of the "second bearing" of the present invention, and rotatably supports an end portion of the gear shaft 12 on the one axial direction D1 side. The second intermediate bearing holder 462 holds the second intermediate bearing 4621. The second intermediate bearing 4621 rotatably supports the end portion of the intermediate shaft 314 on the one axial side D1. The second drive bearing holder 463 is disposed on the inner surface of the second drive shaft through hole 460 and holds the second drive bearing 4631. The second drive bearing 4631 rotatably supports the second drive shaft Ds2.

The gear cover 46 has a flow passage 464. The flow path 464 is a passage for the fluid F and connects the receiving disk part 465 and the inlet port 121 of the motor shaft 1. The receiving tray part 465 has a recess that is recessed vertically downward. The fluid F lifted by the gear (e.g., the fourth gear 321) of the gear portion 3 can be stored in the receiving tray portion 465. In the present embodiment, the gear cover portion 46 has a receiving tray portion 465. The receiving plate part 465 is disposed on the end surface of the gear cover part 46 on the other axial side D2 and extends toward the other axial side D2. The fluid F stored in the receiving plate part 465 is supplied to the flow path 464, and flows into the motor shaft 1 from the inlet 121 at the end on the one axial side D1 of the motor shaft 1.

< 1-4-7. Motor housing 401 >

Further, the motor housing 401 houses the rotor 21 and the stator 22. As described earlier, the housing 4 has the motor housing 401. In the present embodiment, the motor housing 401 is composed of the first housing tube portion 41, the side plate portion 42, and the housing lid portion 43.

< 1-4-7-1. Rotor bearings 4211, 4311 >)

The motor housing 401 is provided with a first rotor bearing holder 431 and a second rotor bearing holder 421. In addition, hereinafter, the first rotor bearing holder 431 and the second rotor bearing holder 421 are sometimes collectively referred to as " rotor bearing holders 421, 431". The housing 4 has rotor bearing retainers 421, 431. The rotor bearing retainers 421 and 431 retain the rotor bearings 4211 and 4311.

Further, hereinafter, the first rotor bearing holder 431, the second rotor bearing holder 421, the first gear bearing holder 422, and the second gear bearing holder 461 are sometimes collectively referred to as " motor bearing holders 421, 431, 422, 461". The housing 4 has motor bearing retainers 421, 431, 422, 461. The motor bearing holders 421, 431, 422, 461 hold the motor bearings 4311, 4211, 4221, 4611.

Further, rotor bearings 4211, 4311 are disposed in the motor housing 401. The rotor bearings 4211, 4311 support the motor shaft 1 rotatably at both sides in the axial direction of the rotor 21. The housing 4 has rotor bearings 4211, 4311. In the present embodiment, the rotor bearings 4211, 4311 are ball bearings. The motor shaft 1 is electrically insulated from the motor housing 401 by rotor bearings 4211, 4311. However, the illustration of the present embodiment does not exclude the structure in which at least either one of the first rotor bearing 4311 and the second rotor bearing 4211 is a rolling bearing other than a ball bearing.

In the present embodiment, the rotor bearings 4211 and 4311 rotatably support both ends of the rotor shaft 11 in the axial direction. In this way, as shown in fig. 2, the electric charge flowing out of the rotor shaft 11 due to the potential variation in the rotor shaft 11 can be discharged to the housing 4 via the gear shaft 12 and the gear portion 3. In particular, in the present embodiment, when the drive device 100 is in the power running state and the regenerative state, the internal teeth of the rotor shaft 11 are in metal contact with the external teeth of the gear shaft 12, and the rotor shaft 11 is conducted with the gear shaft 12. Accordingly, the electric charge of the rotor shaft 11 is discharged to the housing 4 via the above-described path, and further discharged to an external object (the vehicle body 301 or the like) through, for example, the ground connection portion 6 connected to the gear housing 402 and the inverter housing 403 (refer to fig. 2 and 3). Therefore, even if the motor shaft 1 is divided, the occurrence of the electric corrosion at the motor bearings 4311, 4211, 4221, 4611 can be effectively suppressed or prevented.

Fig. 4A is a sectional view showing a configuration example of the motor bearings 4311, 4211, 4221, and 4611. Fig. 4B is a cross-sectional view showing a first modification of the structure of the motor bearings 4311, 4211, 4221, and 4611.

Fig. 4C is a sectional view showing a second modification of the structure of the motor bearings 4311, 4211, 4221, and 4611. Fig. 4A to 4C are cross-sections of the motor bearings 4311, 4211, 4221, and 4611 as viewed in a radial direction with respect to the first rotation axis J1.

For example, as shown in fig. 4A to 4C, the motor bearings 4311, 4211, 4221, 4611 respectively have a pair of races 71 and rolling elements 72. The pair of track rings 71 are arranged concentrically. The rolling elements 72 are disposed between the pair of races 71 so as to be capable of rolling

The pair of track rings 71 includes an inner track ring 711 and an outer track ring 712 disposed radially outward of the inner track ring 711. The inner raceway ring 711 and the outer raceway ring 712 are made of, for example, metal, and have a ring shape surrounding the first rotation axis J1. In fig. 4A, the inner raceway ring 711 is fixed to the radially outer surface of the rotor shaft 11, and the outer raceway ring 712 is fixed to the motor case 401. The plurality of rolling elements 72 are arranged in the circumferential direction between the inner race 711 and the outer race 712.

At least one of the surface of the rolling element 72, the first opposing surface 7110 of the inner race 711 facing the rolling element 72, and the second opposing surface 7120 of the outer race 712 facing the rolling element 72 is preferably electrically insulating. With the above configuration, electric discharge between the pair of raceway rings 71 and the rolling elements 72 can be suppressed or prevented in the motor bearings 4311, 4211, 4221, and 4611. Therefore, the galvanic corrosion of the motor bearings 4311, 4211, 4221, 4611 can be effectively suppressed or prevented.

For example, in fig. 4A, the rolling elements 72 are electrically insulating balls. In this way, the electric discharge between the pair of raceway rings 71 and the rolling elements 72 can be suppressed or prevented in the motor bearings 4311, 4211, 4221, and 4611. Therefore, the galvanic corrosion of the motor bearings 4311, 4211, 4221, 4611 can be effectively suppressed or prevented.

For example, an electrical insulating layer formed by alumite treatment or the like may be disposed on the surface of the rolling element 72. In other words, the rolling elements 72 may have a metal ball and an electrically insulating layer covering the surface of the ball. However, the material and the forming method of the electrically insulating layer of the rolling body 72 are not limited to this example.

Alternatively, in fig. 4A, the rolling elements 72 may be ceramic balls. In this way, the discharge between the rolling elements 72 and the pair of races 71 can be more reliably suppressed or prevented. However, the present invention is not limited to this example, and in fig. 4A, the rolling elements 72 may be electrically insulating balls other than ceramic balls.

In fig. 4A, an electrically insulating layer 7111 formed by alumite treatment or the like is provided on the first opposing face 7110 of the inner coil 711. In other words, the inner track ring 711 may include an electrically insulating layer 7111 and a metal ring portion 7112. The electrically insulating layer 7111 covers the surface of the ring portion 7112 on the outer-side track ring 712 side. However, the materials of the ring portion 7112 and the electrically insulating layer 7111 and the method of forming the electrically insulating layer 7111 are not limited to the above examples.

In fig. 4A, an electrically insulating layer 7121 formed by alumite treatment or the like is provided on the second opposing face 7120 of the outer coil 712. In other words, the outer track ring 712 may include an electrically insulating layer 7121 and a metal ring portion 7122. The electrically insulating layer 7121 covers the surface of the ring portion 7122 on the inner-side track ring 711 side. However, the materials of the ring portion 7122 and the electrical insulating layer 7121 and the method of forming the electrical insulating layer 7121 are not limited to the above examples.

In fig. 4A, at least the surface of the rolling element 72, the first opposing face 7110, and the second opposing face 7120 are all electrically insulating. However, the above examples do not exclude a structure in which at least two of them do not have electrical insulation.

For example, it is preferable that the rolling elements 72 of the second rotor bearing 4211, the first gear bearing 4221, and the second gear bearing 4611 be ceramic balls. Further, the electrically insulating layers 7111 are not arranged on the first and second opposing faces 7110 and 7120 thereof. In this case, the first opposing face 7110 of the inner race 711 of the first rotor bearing 4311 may have electrical insulation, and for example, an electrical insulation layer 7111 may be disposed. Furthermore, the second opposing face 7120 of the outer race 712 of the first rotor bearing 4311 may have an electrically insulating layer, for example, the electrically insulating layer 7111 may be configured.

In this way, in the first rotor bearing 4311 rotatably supporting the other axial side D2 side of the motor shaft 1, which is likely to generate the wobbling due to the accumulated tolerance, the wear resistance of the first opposing surface 7110 and the like can be improved, and the electrical insulation can be ensured. In the motor bearings 4211, 4221, and 4611, the rolling elements 72 are provided as ceramic balls, whereby electrical insulation can be ensured with a simple structure.

Note that, if the motor bearings 4311, 4211, 4221, 4611 are electrically insulated from at least one of the rotor shaft 11 and the motor housing 401, the rolling elements 72, the inner raceway ring 711, and the outer raceway ring 712 may be electrically conductive members.

For example, in fig. 4B, the motor bearings 4311, 4211, 4221, 4611 further have a first insulating member 73. The first insulating member 73 is disposed between the outer race 712 and the motor bearing holders 421, 431, 422, 461. In the present embodiment, the first insulating member 73 has a cylindrical shape extending in the axial direction and has electrical insulation. The material of the first insulating member 73 is, for example, alumite. The outer races 712 of the motor bearings 4311, 4211, 4221, 4611 are fixed to the motor bearing holders 421, 431, 422, 461 via the first insulating member 73. This allows the first insulating member 73 to electrically insulate the outer race 712 from the motor bearing holders 421, 431, 422, 461 of the motor housing 401. For example, an electrical path from the inner race 711 of the first rotor bearing 4311 to the housing cover 43 can be insulated. Further, an electrical path from the inner raceway ring 711 of the second rotor bearing 4211 to the side plate portion 42 can be insulated. The same applies to the other motor bearings 4221 and 4611. Therefore, electric discharge is less likely to occur in the motor bearings 4311, 4211, 4221, and 4611. Therefore, galvanic corrosion of the motor bearings 4311, 4211, 4221, 4611 can be effectively suppressed or prevented.

In fig. 4C, the motor bearings 4311, 4221, 4611 further include a second insulating member 74. The second insulating member 74 is disposed between the inner race 711 and the motor shaft 1 (specifically, the rotor shaft 11). In the present embodiment, the second insulating member 74 has a cylindrical shape extending in the axial direction and has electrical insulation. The material of the second insulating member 74 is, for example, alumite. The inner raceway ring 711 of the motor bearings 4311, 4211, 4221, and 4611 is fixed to the motor shaft 1 (specifically, the rotor shaft 11) via the second insulating member 74. This allows the second insulating member 74 to electrically insulate the inner race 711 from the rotor shaft 11. An electrical path from the outer raceway ring 712 of the motor bearings 4311, 4211, 4221, 4611 to the rotor shaft 11 can be insulated. Therefore, electric discharge is less likely to occur in the motor bearings 4311, 4211, 4221, and 4611. Therefore, galvanic corrosion of the motor bearings 4311, 4211, 4221, 4611 can be effectively suppressed or prevented.

Since the second insulating member 74 is disposed in advance on the inner raceway ring 711, it is not necessary to precisely determine the positions at which the motor bearings 4311, 4211, 4221, and 4611 are disposed on the rotor shaft 11, unlike the case where the second insulating member 74 is disposed on the rotor shaft 11 in advance. Therefore, the arrangement of the motor bearings 4311, 4211, 4221, 4611 becomes easy. When the outer ring track 712 of the motor bearings 4311, 4211, 4221, and 4611 is press-fitted into the motor bearing holders 421, 431, 422, and 461, the insulating member is not disposed on the outer ring track 712 side, and the life of the insulating member can be increased.

In addition, the motor bearings 4311, 4211, 4221, 4611 may include both the first insulating member 73 and the second insulating member 74, without being limited to the examples of fig. 4B and 4C. In addition, the above structures can be arbitrarily combined unless a contradiction is particularly generated. In this way, galvanic corrosion of the motor bearings 4311, 4211, 4221, 4611 can be more effectively suppressed or prevented.

< 1-4-8. Gear housing 402 >

The gear housing 402 houses the gear portion 3. As previously described, the housing 4 has a gear housing 402. In the present embodiment, the gear housing 402 is configured by the side plate portion 42, the second housing tubular portion 45, and the gear cover portion 46, and houses the reduction gear unit 31, the differential unit 32, and the like.

A fluid reservoir P for storing the fluid F is disposed at a lower portion in the gear housing 402. A part of the gear portion 3 (for example, the fourth gear 321) is immersed in the fluid reservoir portion P. The fluid F stored in the fluid storage portion P is lifted by the operation of the gear portion 3 and supplied to the inside of the gear housing 402. For example, when the fourth gear 321 of the differential device 32 rotates, the fluid F is kicked up by the tooth surface of the fourth gear 321. A part of the fluid F that is kicked up is supplied to the gears and bearings of the reduction gear 31 and the differential gear 32 in the gear housing 402 and used for lubrication. Further, the other part of the lubricating liquid CL that is kicked up is supplied to the inside of the motor shaft 1, and is supplied to the rotor 21 and the stator 22 of the motor 2, and each bearing in the gear housing 402, for cooling and lubrication.

< 1-4-8-1. Gear bearings 4221, 4611 >

The gear housing 402 is provided with a first gear bearing holder 422, a second gear bearing holder 461, and gear bearings 4221 and 4611. In the present embodiment, the gear bearings 4221 and 4611 rotatably support both ends in the axial direction of the gear shaft 12.

< 1-4-8-2 > drive bearings 4241, 4631 >

Further, the gear housing 402 is provided with a first drive bearing holder 424, a second drive bearing holder 463, a first drive bearing 4241, and a second drive bearing 4631. In addition, hereinafter, first drive bearing 4241 and second drive bearing 4631 are sometimes collectively referred to as "drive bearings 4241, 4631". The drive bearings 4241 and 4631 rotatably support both ends in the axial direction of the drive shaft Ds. The housing 4 has drive bearings 4241, 4631.

Drive bearings 4241, 4631 are roller bearings. Fig. 5 is a sectional view showing a configuration example of the first drive bearing 4241 and the second drive bearing 4631. Fig. 5 is a cross section of the drive bearings 4241 and 4631 as viewed in a radial direction with reference to the third rotation axis J3.

For example, as shown in fig. 5, the drive bearings 4241, 4631 have a pair of raceway rings 81 and rolling elements 82, respectively. The pair of track rings 81 are arranged concentrically. The rolling elements 82 are disposed between the pair of raceway rings 81 so as to be capable of rolling, and have a shape having a longitudinal direction in the axial direction. The pair of track rings 81 includes an inner track ring 811 and an outer track ring 812 disposed radially outward of the inner track ring 811. The inner raceway ring 811 and the outer raceway ring 812 are made of, for example, metal, and have a ring shape surrounding the third rotation axis J3. In fig. 5, an inner raceway ring 811 is fixed to the radially outer surface of the drive shaft Ds, and an outer raceway ring 812 is fixed to the gear housing 402. The plurality of rolling elements 82 are arranged in the circumferential direction between the inner raceway ring 811 and the outer raceway ring 812. The rolling elements 82 have conductivity and are made of, for example, metal. Therefore, the drive bearings 4241, 4631 have lower electric resistance than the motor bearings 4311, 4211, 4221, 4611.

As described above, since the rolling elements 82 of the drive bearings 4241, 4631 which are roller bearings have a shape having a longitudinal direction in the axial direction, the contact area with the pair of raceway rings 81 can be further increased as compared with a ball bearing, for example. The drive bearings 4241, 4631 have lower electric resistance than the motor bearings 4311, 4211, 4221, 4611. That is, the drive bearings 4241, 4631 have higher conductivity. On the other hand, as described above, the motor bearings 4311, 4211, 4221, 4611 supporting the motor shaft 1 in the motor housing 401 are electrically insulated from the motor housing 401. Therefore, as shown in fig. 2, when the drive device 100 is in the power running state and the regenerative state, the electric charge flowing out from the rotor shaft 11 due to the potential variation in the motor shaft 1 (particularly, the rotor shaft) is discharged to the gear housing 402 via the gear shaft 12, the first gear 311, the second gear 312, the third gear 313, the intermediate shaft 314, the differential device 32 including the fourth gear 321, the drive shaft Ds, and the drive bearings 4241, 4631. Further, the electric charge is discharged to, for example, a vehicle body 301 (see fig. 3) of a vehicle 300 in which the driving device 100 is installed, through a ground connection portion 6 connected to a gear housing 402, an inverter housing 403, and the like of the housing 4. Therefore, the occurrence of galvanic corrosion of the motor bearings 4311, 4211, 4221, 4611 can be more effectively suppressed or prevented.

Further, the electric charge is discharged through the drive bearings 4241, 4631, so that the static electricity eliminating path between the gear shaft 12 and the gear housing 402 passes through the first gear 311, the second gear 312, the third gear 313, the intermediate shaft 314, the differential device 32 including the fourth gear 321, the drive shaft Ds, and the drive bearings 4241, 4631. Therefore, the static electricity eliminating path from the motor shaft 1 to the housing 4 can be further extended. Therefore, the potential difference between the motor shaft 1 and the drive bearing holders 424 and 463 that hold the drive bearings 4241 and 4631 of the housing 4 can be further increased. Therefore, electric charge is easily discharged from the motor shaft 1 (particularly, the rotor shaft) to the housing 4.

The pair of raceway rings 81 of the drive bearings 4241 and 4631 are lubricated by the lubricant 83. Preferably, the lubricating material 83 is more electrically conductive than, for example, the fluid F. For example, the lubricating material 83 can be conductive grease. In the conductive grease, a conductive material such as copper powder or carbon powder is added to a lubricating oil such as grease. The improvement in the electrical conductivity of the lubricant 83 can contribute to the suppression or prevention of the occurrence of the electric corrosion. However, the above examples do not exclude a structure in which the lubricant 83 is not disposed, and do not exclude a structure in which the lubricant 83 has a conductivity not higher than that of the fluid F, for example.

< 1-4-8-3. Intermediate bearings 4231, 4621 >

Further, the gear housing 402 is provided with a first intermediate bearing holder 423, a second intermediate bearing holder 462, and intermediate bearings 4231 and 4621. The intermediate bearings 4231 and 4621 rotatably support both axial ends of the intermediate shaft 314. The housing 4 has intermediate bearings 4231, 4621.

In the present embodiment, the intermediate bearings 4231, 4621 are roller bearings. Fig. 6 is a sectional view showing a configuration example of the first intermediate bearing 4231 and the second intermediate bearing 4621. Fig. 6 is a cross section of the intermediate bearings 4231 and 4621 as viewed in a radial direction with reference to the second rotation axis J2.

For example, as shown in fig. 6, the intermediate bearings 4231, 4621 have a pair of raceway rings 91 and rolling elements 92, respectively. The pair of track rings 91 are arranged concentrically. The rolling elements 92 are disposed between the pair of races 91 so as to be capable of rolling, and have a shape having a longitudinal direction in the axial direction. The pair of races 91 includes an inner race 911 and an outer race 912 disposed radially outward of the inner race 911. The inner race 911 and the outer race 912 are made of metal, for example, and have a ring shape surrounding the second rotation axis J2. In fig. 6, an inner race 911 is fixed to a radially outer surface of the intermediate shaft 314, and an outer race 912 is fixed to the gear housing 402. The plurality of rolling elements 92 are arranged in the circumferential direction between the inner race 911 and the outer race 912. The rolling elements 92 are conductive and made of metal, for example. Therefore, the intermediate bearings 4231, 4621 have lower electric resistance than the motor bearings 4311, 4211, 4221, 4611.

As shown in fig. 2, when the drive device 100 is in the power running state and the regenerative state, the electric charge flowing out of the rotor shaft 11 due to the potential variation in the rotor shaft 11 can flow to the intermediate shaft 314 via the gear shaft 12, the first gear 311, and the second gear 312. Therefore, the electric charge can be further released to the gear housing 402 through the intermediate shaft 314 and the intermediate bearings 4231, 4621. Further, the electric charge can be discharged to, for example, a vehicle body 301 (see fig. 3) of a vehicle 300 in which the driving device 100 is installed, through a ground connection portion 6 connected to a gear housing 402, an inverter housing 403, and the like of the housing 4. Therefore, the occurrence of galvanic corrosion of the motor bearings 4311, 4211, 4221, 4611 can be more reliably suppressed or prevented.

Further, the pair of raceway rings 91 of the intermediate bearings 4231 and 4621 are lubricated by a lubricant 93. Preferably, the lubricating material 93 has a higher electrical conductivity than, for example, the fluid F. For example, the lubricating material 93 can employ conductive grease. In the conductive grease, a conductive material such as copper powder or carbon powder is added to a lubricating oil such as grease. The improvement in the electrical conductivity of the lubricating material 93 can contribute to the suppression or prevention of the occurrence of the galvanic corrosion. However, the above examples do not exclude a structure in which the lubricant 93 is not disposed, and do not exclude a structure in which the lubricant 93 has a higher conductivity than, for example, the fluid F.

The illustration of the present embodiment does not exclude the configuration in which the intermediate bearings 4231 and 4621 are not roller bearings. For example, it is not excluded that the intermediate bearings 4231, 4621 are ball bearings or slide bearings.

< 1-5. Fluid circulation portion 5 >

Next, the fluid circulation unit 5 will be explained. The fluid circulation portion 5 has a piping portion 51, a pump 52, a cooling unit 53, and a fluid reservoir 54.

The piping portion 51 connects the pump 52 to a fluid reservoir 54 disposed inside the first housing tube portion 41. The pump 52 sucks the fluid F stored in the fluid storage portion P and supplies the fluid F to the fluid reservoir 54. In the present embodiment, the pump 52 is an electric pump.

The cooling unit 53 is disposed between the pump 52 and the fluid reservoir 54 in the pipe portion 51. That is, the fluid F sucked by the pump 52 is sent to the fluid reservoir 54 through the pipe 51 via the cooling unit 53. For example, a coolant such as water supplied from the outside is supplied to the cooling unit 53. The cooling unit 53 performs heat exchange between the refrigerant and the fluid F to reduce the temperature of the fluid F.

The fluid reservoir 54 is a tray disposed vertically above the stator 22 inside the motor housing 401. A dropping hole (not shown) is formed in the bottom of the fluid reservoir 54, and the fluid F is dropped from the dropping hole to cool the motor 2. The dripping hole is formed, for example, above the coil edge 2221 of the coil portion 222 of the stator 22, and the coil portion 222 is cooled by the fluid F.

< 1-6. Ground connection part 6 >

The ground connection 6 grounds the housing 4 to an external object. As described above, the driving device 100 further includes the ground connection portion 6. In the present embodiment, the ground connection portion 6 is a conductive cable in which a conductive wire is covered with an insulation. One end of the conductive cable is electrically connected to the housing 4, and the other end is electrically connected to, for example, a vehicle body 301 of the vehicle 300 (see fig. 3). In this way, the housing 4 and an object outside the housing (for example, the body 301 of the vehicle 300) can be grounded via the ground connection portion 6. Therefore, the electric charge discharged from the motor shaft 1 (particularly, the rotor shaft 11) to the housing 4 can be discharged to an external object, and thus the potential of the housing 4 can be suppressed or prevented from rising. The occurrence of galvanic corrosion at the motor bearings 4311, 4211, 4221, 4611 can be more reliably suppressed or prevented.

Preferably, as shown in fig. 3, the ground connection portion 6 is disposed in the inverter case 403. For example, one end of the conductive cable is electrically connected to the inverter case 403. In this way, the ground connection portion 6 can also ground the inverter case 403 to an object outside the case 4 (for example, the vehicle body 301 of the vehicle 300). Therefore, it is also possible to suppress or prevent an increase in the ground potential of the inverter 4031 housed in the inverter case 403. However, the above example does not exclude a configuration in which the ground connection portion 6 is disposed in a portion of the case 4 other than the inverter case 403. For example, the ground connection portion 6 may be connected to the motor housing 401, the gear housing 402 (see fig. 2), and the like.

< 1-7. Variation of embodiment >

Next, a modification of the embodiment will be described with reference to fig. 7 and 8. Fig. 7 is a schematic configuration diagram of a driving device 100 according to a modification. Fig. 8 is a conceptual diagram illustrating a static electricity elimination path of the driving device 100 in the modification. Fig. 7 and 8 are conceptual diagrams, and the arrangement and dimensions of the respective portions are not necessarily the same as those of the actual drive device 100. In fig. 8, a thick solid line with an arrow indicates an electrostatic eliminating path. Hereinafter, a structure different from the above embodiment will be described. Note that the same components as those in the above embodiment are denoted by the same reference numerals, and description thereof may be omitted.

In the modification, the motor shaft 1 has a cylindrical shape extending in the axial direction. The drive shaft Ds is inserted into the cylindrical motor shaft 1 extending in the axial direction and extends along the first rotation axis J1. In this way, it is not necessary to secure a space for disposing the drive shaft Ds radially outward of the motor shaft 1. Therefore, the size of the drive device 100 in the direction perpendicular to the axial direction can be further reduced. Therefore, the driving device 100 can be miniaturized. Further, the gap between the drive shaft Ds and the motor shaft 1 can be used as a flow path through which the fluid F functioning as a refrigerant flows.

The drive shaft Ds is rotatable about the first rotation axis J1. That is, the rotational axis of the drive shaft Ds coincides with the first rotational axis J1. Since the rotation centers of the drive shaft Ds and the motor shaft 1 coincide with each other, the gap therebetween in the radial direction with respect to the first rotation axis J1 can be made constant. Therefore, the fluid F can be caused to flow through the gap without variation in the flow rate and the flow resistance in the circumferential direction with respect to the first rotation axis J1.

Specifically, a part of the first drive shaft Ds1 (that is, a central part in the axial direction) is disposed inside the motor shaft 1. The first drive shaft Ds1 is disposed concentrically with the motor shaft 20 when viewed in the axial direction. The end portion of the first drive shaft Ds1 on the other axial side D2 is disposed on the other axial side D2 of the motor shaft 1.

In the modification, the first drive shaft through hole 432 through which the first drive shaft Ds1 is inserted is disposed in the housing cover portion 43 instead of the side plate portion 42. The housing cover portion 43 also has a first drive shaft through hole 432. The first drive shaft through hole 432 axially penetrates the housing cover portion 43. The center of the first drive shaft penetration hole 432 coincides with the first rotation axis J1. An oil seal (not shown) for sealing between the first drive shaft Ds1 and the first drive shaft through hole 432 is disposed in a gap therebetween.

The housing lid portion 43 further includes a first drive bearing holder 433 and a first drive bearing 4331. The first drive bearing holder 433 is disposed on the inner surface of the first drive shaft through hole 432, and holds the first drive bearing 4331. The first drive bearing 4331 rotatably supports the first drive shaft Ds1.

Further, the first drive bearing holder 433 is connected to the pipe portion 51. Therefore, the first drive bearing 4331 is lubricated and cooled by a part of the fluid F flowing in the pipe portion 51. Further, the fluid F flows into the inside of the motor shaft 1. That is, in the modification, the opening at the end portion on the other side D2 side in the axial direction of the motor shaft 1 constitutes the inflow port 112 of the fluid F. A part of the fluid F flowing into the motor shaft 1 from the inlet port 112 flows to the rotor through-hole 2111 through the shaft through-hole 111. The remaining portion is discharged from the end portion on the one axial direction D1 side of the motor shaft 1 and is accumulated in the fluid reservoir P.

The second drive shaft Ds2 and the differential device 32 are disposed on the one axial side D1 of the motor shaft 1. A second gear bearing 471, which rotatably holds the end portion of the motor shaft 20 on the one axial side D1, is held by the second gear bearing holder 47. That is, the housing 4 has the second gear bearing holder 47 and the second gear bearing 471 in place of the second gear bearing holder 461 and the second gear bearing 4611. The second gear bearing holder 47 is disposed on the other axial side D2 side of the differential device 32, and is disposed on the side plate portion 42 or the second casing tube portion 45.

In the modification, the motor shaft 1 is electrically insulated from the motor housing 401 by the motor bearings 4311, 4211, 4221, 4611, as in the above embodiment. Further, the first drive bearing 4331 and the second drive bearing 4631 are roller bearings. In the modification, the first drive bearing 4331 and the second drive bearing 4631 may be collectively referred to as "drive bearings 4331 and 4631". The drive bearings 4331, 4631 have lower electric resistance than the motor bearings 4311, 4211, 4221, 4611. Further, as described above, since the rolling elements 82 of the drive bearings 4331, 4631 which are roller bearings have a shape having a longitudinal direction in the axial direction, the contact area with the pair of raceway rings 81 can be further increased as compared with a ball bearing, for example. Therefore, the drive bearings 4331, 4631 have higher conductivity.

Therefore, as shown in fig. 8, when the drive device 100 is in the power running state and the regenerative state, the electric charge flowing out from the rotor shaft 11 due to the potential variation in the motor shaft 1 (particularly, the rotor shaft) is discharged to the drive shaft Ds via the gear shaft 12, the first gear 311, the second gear 312, the intermediate shaft 314, the third gear 313, and the differential device 32 including the fourth gear 321. Further, the above electric charge is discharged to the motor housing 401 of the housing 4 through the first drive bearing 4331, and is discharged to the gear housing 402 of the housing 4 through the second drive bearing 4631. These charges are discharged to, for example, a vehicle body 301 (see fig. 3) of a vehicle 300 in which the driving device 100 is installed, through a ground connection portion 6 connected to a gear housing 402, an inverter housing 403, and the like of the housing 4. Therefore, the occurrence of galvanic corrosion of the motor bearings 4311, 4211, 4221, 4611 can be more effectively suppressed or prevented.

Further, the electric charge is discharged through the drive bearings 4331, 4631, so that the static electricity eliminating path between the gear shaft 12 and the gear housing 4 passes through the first gear 311, the second gear 312, the third gear 313, the intermediate shaft 314, the differential gear 32 including the fourth gear 321, the drive shaft Ds, and the drive bearings 4331, 4631. Therefore, the static electricity eliminating path from the motor shaft 1 to the housing 4 can be further extended. Therefore, the potential difference between the motor shaft 1 and the drive bearing holders 433 and 463 that hold the drive bearings 4331 and 4631 of the housing 4 can be further increased. Therefore, electric charge is easily discharged from the motor shaft 1 (particularly, the rotor shaft) to the housing 4.

In the modification, similarly to the above embodiment, the intermediate bearings 4231, 4621 have lower electric resistance than the motor bearings 4311, 4211, 4221, 4611. Therefore, as shown in fig. 8, when the drive device 100 is in the power running state and the regenerative state, the electric charge flowing out from the rotor shaft 11 due to the potential variation in the rotor shaft 11 is discharged to the gear housing 402 via the gear shaft 12, the first gear 311, the second gear 312, the intermediate shaft 314, and the intermediate bearings 4231, 4621. Further, the electric charge can be discharged to, for example, a vehicle body 301 (see fig. 3) of a vehicle 300 on which the driving device 100 is mounted, through a ground connection portion 6 connected to a gear housing 402, an inverter housing 403, and the like of the housing 4. Therefore, the occurrence of galvanic corrosion of the motor bearings 4311, 4211, 4221, and 4611 can be more reliably suppressed or prevented.

< 2. Other >)

The embodiments of the present invention have been described above. The scope of the present invention is not limited to the above embodiments. The present invention can be implemented by adding various modifications to the above-described embodiment without departing from the scope of the present invention. Note that the matters described in the above embodiments can be arbitrarily combined as appropriate within a range not inconsistent with each other.

In the present embodiment and the modification, the present invention is applied to the in-vehicle drive device 100. The present invention is not limited to this example, and may be applied to a drive device used for an application other than a vehicle.

< 3. Summary >

Hereinafter, the embodiments and the modifications thereof explained so far are summarized.

For example, the driving device disclosed in the present specification has a configuration (first configuration) including:

a motor shaft that extends along a first rotation axis extending in an axial direction and is rotatable centering on the first rotation axis;

a rotor rotatable with the motor shaft;

a stator disposed radially outward of the rotor;

a gear portion connected to one axial side of the motor shaft; and

a housing that houses the rotor, the stator, and the gear portion,

the housing has:

a housing tube portion that extends in an axial direction and that holds the stator on an inner side surface;

a first cover portion attached to the other end portion in the axial direction of the housing tube portion;

a second cover portion that is disposed on one axial side of the outer shell cylinder portion and that extends in a direction intersecting the first rotation axis; and

a motor bearing rotatably supporting the motor shaft,

the motor bearing includes:

a first bearing that is a rolling bearing disposed in the first lid and rotatably supports the motor shaft on the other axial side of the rotor; and

a second bearing disposed on the second cover and rotatably supporting the motor shaft on one side in an axial direction of the rotor,

the motor shaft and the first cover portion are electrically insulated by a first bearing.

The drive device of the first configuration described above may be configured as a configuration (second configuration) in which,

the motor shaft has:

a first shaft that holds the rotor; and

and a second shaft connected to one axial end of the first shaft and to which the gear portion is connected.

Further, the drive device of the first configuration or the second configuration may be configured as a configuration (third configuration) in which,

the second cover is a side plate portion disposed at one axial end of the outer shell cylinder portion and covering the one axial end of the outer shell cylinder portion,

the second motor bearing is a rolling bearing disposed at the side plate portion, rotatably supports the motor shaft at one side in an axial direction of the rotor,

the motor shaft is electrically insulated from the side plate portion by the second bearing.

Further, the drive device of the third configuration may be configured as (a fourth configuration) in which,

the first bearing has a greater electrical resistance than the second bearing.

Further, the drive device of any one of the first to fourth configurations described above may be configured as a configuration (fifth configuration) in which,

the motor bearing includes:

a pair of track rings arranged concentrically; and

a rolling body disposed between the pair of races so as to be capable of rolling,

the pair of track rings includes an inner track ring and an outer track ring disposed radially outward of the inner track ring,

at least one of at least a surface of the rolling element, a first facing surface of the inner raceway ring facing the rolling element, and a second facing surface of the outer raceway ring facing the rolling element has an electrical insulation property.

Further, the drive device of the fifth configuration described above may be configured as a configuration (sixth configuration) in which,

the rolling bodies are ceramic balls.

Further, the drive device of the fifth configuration may be structured as (a seventh configuration) in which,

the first facing surface of the first bearing has electrical insulation,

the rolling elements of the second bearing are ceramic balls.

Further, the drive device of any one of the fifth configuration to the seventh configuration may be configured as a configuration (eighth configuration) in which,

the housing further having a motor bearing retainer that retains the motor bearing,

the motor bearing further has a first insulating member disposed between the outer race and the motor bearing holder,

the outer race ring is fixed to the motor bearing holder by the first insulating member.

Further, the drive device of any one of the fifth configuration to the eighth configuration may be configured as a configuration (ninth configuration) in which,

the motor bearing further has a second insulating member disposed between the inner raceway ring and the motor shaft,

the inner race ring is fixed to the motor bearing by the second insulating member.

Further, the drive device of any one of the first to ninth configurations may be configured as a structure (tenth configuration) in which,

further comprising a fluid flow path that supplies fluid that lubricates the motor bearing to the motor bearing.

Further, the drive device of any one of the first to tenth configurations described above may be configured as a configuration (eleventh configuration) in which,

the gear portion has:

a first gear fixed to a radially outer side surface of the motor shaft at one side in an axial direction of the motor shaft;

an intermediate shaft that extends along a second rotation axis extending in an axial direction and is rotatable centering on the second rotation axis;

a second gear fixed to a radially outer side surface of the intermediate shaft and meshed with the first gear;

a third gear fixed to a radially outer side surface of the intermediate shaft; and

a differential device having a fourth gear that meshes with the third gear, outputting torque of the fourth gear to a drive shaft,

the housing further has a drive bearing that rotatably supports both axial ends of the drive shaft,

the first bearing is a ball bearing,

the drive bearing is a roller bearing and,

the drive bearing has a lower resistance than the first bearing.

Further, the drive device according to any one of the first to eleventh configurations may be structured (twelfth configuration),

the housing further has an intermediate bearing that supports both axial ends of the intermediate shaft to be rotatable,

the intermediate bearing has a lower electrical resistance than the first bearing.

Further, the drive device of any one of the first to twelfth configurations described above may be structured (thirteenth configuration) in which,

the grounding connection part is used for grounding the shell and an external object.

Further, the drive device of the thirteenth configuration may be structured (fourteenth configuration) in which,

the housing further has an inverter housing that houses an inverter that supplies a drive current to the stator,

the ground connection portion is disposed on the inverter case.

Further, the drive device of any one of the first to fourteenth configurations described above may be structured (fifteenth configuration) in which,

the motor shaft is in a cylindrical shape extending in the axial direction,

the drive shaft is inserted into the motor shaft.

Further, the vehicle disclosed in the present specification may be given a structure (sixteenth structure) in which,

a driving device including any one of the first to fifteenth structures.

Industrial applicability of the invention

The present invention is useful for, for example, an apparatus having a motor in which a motor shaft is rotatably supported by a rolling bearing. The above-described device is useful for in-vehicle applications, and is also useful for applications other than in-vehicle applications.

Claims (16)

1. A drive device, comprising:

a motor shaft that extends along a first rotation axis extending in an axial direction and is rotatable centering on the first rotation axis;

a rotor rotatable with the motor shaft;

a stator disposed radially outward of the rotor;

a gear portion connected to one axial side of the motor shaft; and

a housing that houses the rotor, the stator, and the gear portion,

the housing has:

a housing tube portion that extends in an axial direction and that holds the stator on an inner side surface;

a first cover portion attached to the other end portion in the axial direction of the housing tube portion;

a second cover portion that is disposed on one axial side of the outer shell cylinder portion and that extends in a direction intersecting the first rotation axis; and

a motor bearing rotatably supporting the motor shaft,

the motor bearing includes:

a first bearing that is a rolling bearing disposed in the first lid and rotatably supports the motor shaft on the other axial side of the rotor; and

a second bearing disposed on the second cover and rotatably supporting the motor shaft on one side in an axial direction of the rotor,

the motor shaft is electrically insulated from the first cover portion by a first bearing.

2. The drive of claim 1,

the motor shaft has:

a first shaft that holds the rotor; and

and a second shaft connected to one axial end of the first shaft and to which the gear portion is connected.

3. The drive of claim 1,

the second cover is a side plate portion that is disposed at one axial end portion of the outer shell cylinder portion and covers the one axial end portion of the outer shell cylinder portion,

the second motor bearing is a rolling bearing disposed at the side plate portion, rotatably supports the motor shaft at one side in an axial direction of the rotor,

the motor shaft is electrically insulated from the side plate portion by the second bearing.

4. The drive of claim 3,

the first bearing has a greater electrical resistance than the second bearing.

5. The drive device according to any one of claims 1 to 4,

the motor bearing includes:

a pair of track rings arranged concentrically; and

a rolling body disposed between the pair of races so as to be capable of rolling,

the pair of track rings includes an inner track ring and an outer track ring disposed radially outward of the inner track ring,

at least one of a surface of the rolling element, a first facing surface of the inner raceway ring facing the rolling element, and a second facing surface of the outer raceway ring facing the rolling element has an electrical insulating property.

6. The drive of claim 5,

the rolling bodies are ceramic balls.

7. The drive of claim 5,

the first opposed surface of the first bearing has an electrical insulating property,

the rolling elements of the second bearing are ceramic balls.

8. The drive of claim 5,

the housing further having a motor bearing retainer that retains the motor bearing,

the motor bearing further has a first insulating member disposed between the outer race and the motor bearing holder,

the outer race is fixed to the motor bearing holder by the first insulating member.

9. The drive of claim 5,

the motor bearing further has a second insulating member disposed between the inner raceway ring and the motor shaft,

the inner race ring is fixed to the motor shaft through the second insulating member.

10. The drive device of claim 1,

further comprising a fluid flow path that supplies fluid that lubricates the motor bearing to the motor bearing.

11. The drive device of claim 1,

the gear portion has:

a first gear fixed to a radially outer side surface of the motor shaft at one side in an axial direction of the motor shaft;

an intermediate shaft that extends along a second rotation axis extending in an axial direction and is rotatable centering on the second rotation axis;

a second gear fixed to a radially outer side surface of the intermediate shaft and meshed with the first gear;

a third gear fixed to a radially outer side surface of the intermediate shaft; and

a differential device having a fourth gear that meshes with the third gear, outputting torque of the fourth gear to a drive shaft,

the housing further has a drive bearing that rotatably supports both axial ends of the drive shaft,

the first bearing is a ball bearing,

the drive bearing is a roller bearing and,

the drive bearing has a lower resistance than the first bearing.

12. The drive device of claim 1,

the housing further has an intermediate bearing that supports both axial ends of the intermediate shaft to be rotatable,

the intermediate bearing has a lower electrical resistance than the first bearing.

13. The drive of claim 1,

the grounding connection part is used for grounding the shell and an external object.

14. The drive of claim 13,

the housing further has an inverter housing that houses an inverter that supplies a drive current to the stator,

the ground connection portion is disposed on the inverter case.

15. The drive of claim 1,

the motor shaft is in a cylindrical shape extending in the axial direction,

the drive shaft is inserted into the motor shaft.

16. A vehicle, characterized in that,

comprising a drive device according to any one of claims 1 to 15.

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